Calculation of the Electrical Resistivity of Liquid Iron in the Earth's Core

Abstract

SEVERAL empirical values for the electrical resistivity of the Earth's fluid core have been proposed¹. The latest estimates are those of Gardiner and Stacey² which correct earlier estimates by Stacey³. They use data on the electrical resistivity and its temperature coefficient for liquid iron and its alloys at 1,800 K and combine this with the observed pressure coefficient of resistivity in solid iron-nickel alloys at 100 kbar. These results are then extrapolated to the core temperatures (∼ 4,000 K) and pressures (3,000 kbar) assuming the temperature and pressure effects to be additive. As the authors of ref. 2 admit, this latter assumption is of doubtful validity. Obviously such large extrapolations involve considerable uncertainties; since the core resistivity is a vital parameter in the theories of the origin of the geomagnetic field it is important to assess the validity of the existing estimates.